As a radio communication unit, wireless IC tags for updating information between the IC tag and a reader device become widespread and prosperous. The important usages of the wireless IC tags include logistics such as product inventory management or container and pallet management. In other words, the utilization of wireless IC tags for tracking and managing a material transportation status by attaching the wireless IC tags to management objects such as materials is under consideration. On the other hand, transportation of materials is actively underway multi-nationally owing to activization of trades or internationalization of company activities, etc.
In general, such wireless IC tags are made up of IC chips and antennas which are capable of storing information. The wireless IC tags can transmit/receive data to/from a device referred to as a reader/writer, by means of radio waves (Patent Document 1, for instance). Among them, in particular, a wireless IC tag, which uses a radio wave frequency of 300 MHz or more and does not have a power source incorporated therein, is deemed to be suitable for usages of replacement of bar codes, etc., because of its long communicable distance with the reader/writer and its comparatively low price (Patent Document 2, for instance).
As to radio waves used for communication with the wireless IC tag and the reader/writer, the greater transmission power is, the longer communication distance between the wireless IC tag and the reader/writer is. Further, the lower communication frequency is, the smaller propagation loss in air is, and therefore, the longer communication distance is. With respect to frequencies of available radio waves and their output levels, however, the limits defined on a country-by-country basis are present, and, among the limits defined in countries, a frequency and transmission power are selected such that the maximum effect is attained, and a communication system between the wireless IC tag and the reader/writer is designed. In the wireless IC tags, antennas are designed so as to obtain impedance characteristics and resonance characteristics responsive to the limits determined in countries. In conventional wireless IC tags, therefore, matching is attempted in only one frequency band, communication with the reader/writer employing another frequency band is impossible and difficult, and a problem arises with reading precision of the wireless IC tag.    Patent Document 1: Japanese Patent No. 2553641    Patent Document 2: Japanese Patent Application Laid-open No. 2002-298106